Electric plug



March 25, 1947. I M GUERNSEY -2,417,928

ELECTRI C PLUG Filed Aug. 28, 1945 Max M I INVE NTOR ATTORNEY Patented Mar. 25, 1947 UNITED STATES PATENT OFFlCEQ Max M. Guernsey. Steilacoom, Wash. Application August 28, 1945, Serial No. 613,044

1 This invention relates to electric plugs, and especially to those adapted to connect a small electric motor to either a 220-volt or a 110-volt circuit, and has for its main object to provide a plug which may be changed for use with one circuit or the other without disconnecting or changing its connections with the motor or changing the motor wiring arrangement. I attain this and other objects by the devices and arrangements illustrated in the accompanying drawings, in Which- Fig. 1 is a perspective view of the plug body, the removable parts having been removed there- 4 Claims. (01. 173-361) from; Fig. 2 is a perspective view of the insert, H

showing it in the relative position for connecting with the 220-volt circuit; Fig. 3 is a similar view thereof, showing it in the relative position for connecting with the 110-vo1t circuit; Fig. 4 is a plan of the cover of the plug; Figs. 5 and 6 are diagrammatic plan and elevation views of the plug, with the cover removed, showing the insert in the position for connecting with the 110-volt circuit; and Figs. 7 and 8 are similar views showing the insert in a position for connection with the 220-volt circuit.

Similar numerals of reference refer to similar parts throughout theseveral views.

g Small electric motors are commonly equipped with a terminal box having four terminals therein, connected to suitable parts of the electric circuits therein. These terminal boxes are provided with means for connecting together one or two pairs of such terminals, depending on Whether the motor is to be connected to a 220-volt or a 110-vo1t circuit respectively. The standard outlets for said two circuits differ in that for the 220-volt circuit the slots for the receipt of the plug connecting fingers lie at right-angles to each 'other while for the 110-volt circuit the slots lie parallel to each other. Therefore, at the present time, when it is desired to change the motor from one circuit to another of a different voltage, it is necessary to rearrange the connections in the terminal box at the motor and also to replace the plu by which it is to be connected to the new circuit with another plug adapted to engage the outlet of the said new circuit.

I have provided a means of eliminating both said steps by connecting each of the four wires in the motor terminal box by separate wires (preferably by a four-wire cord) directly to my improved plug, which is provided with means whereby one such plug finger may be changed from one to the other position relatively to the other plu finger, and in so doing the proper pairs of wires are connected together in the improved plug, so that it is only necessary toremove the cover that holds the parts of the plug together to change both the position of the one finger in relation to the other and to efiect the necessary changes to the motor wiring, and this is accomplished without the necessity of disconnecting any wiring terminals either at the motor or at the plug.

Referring, now, to the drawings, the main plug body 9 is made of insulating material and is provided with a single fixed vertical contact finger in extending out therefrom. This finger I0 is flat in cross-section and is adapted to fit in one of the contact slots in the outlet in the usual manner. The outer face of the body 9 is provided with a square recess or cavity I l adapted to receive the following described insert l2, said insert being adapted to occupy either. one of two positions in said cavity l I.

The insert I2 comprises a square body of insulating material having, at a suitable point therein, the complementary contact finger l3 extending therefrom. This finger I 3 is positioned so that it will extend from the plug 9 with its major axis in positions either parallel with or at right-angles to the major axis of the said contact finger I0, depending on the position of theinsert l2 in the cavity ll. Two opposite corners of this insert l2 are provided with angular metallic contact plates l4 and I5. As seen in Figs. 2 and 3 the contact plate I5 is electrically connected to the said vertical contact finger l3.

Referring to Fig. 1 it will be observed that the vertical walls of the cavity II are provided with four contact plates l6, ll, 18 and I9. Designating the four wires of the cord from the motor as a, b, c and d and referring to the diagram in Figs. 5 and 6, the wire a is permanently electrically connected to the contact plate Hi; the wire I) to plate H; the wire 0 to plate l8; and the wire d to plate l9. Also the wire a is electrically connected through the plate It to the fixed contact finger I0.

When the insert I2 is placed, as shown in Fig.

5, for 110-volt circuit, it will be seen that the corner contact plate M of the insert touches and thus connects together the two contact I plates l6 and H in the cavity, and that the contact plate l5, which is connected to the contact finger l3, touches the contact plates 3 and I9 contact plate I 4 and the two wires c and d are connected together by the contact plate l5, and that the major cross-sectional axes of the two contact fingers l8 and (3 are parallel with each other.

By removing the insert l2 from the cavity l I and then turning it through a right-angle and reinserting it into the cavity H, it will be seen by Figs. '7 and 8 that th corner contact plate 14 of the insert now touches the contact plates H and 18, thus the wires b and c from the motor are connected together, while the wire a connects directly with the contact finger l8 and the 1 wire d connects through the contact plates. J9

and I5 with the contact finger l3, and the major cross-sectional aXes of the contact fingers, l0 and I3 lie at right-angles to each other. U Thus it will be seen that for the 110-volt circuit, the wires a and b are combined and act as one while the wires c and d are similarly combined; while for the 220-volt circuit the wires 11 and c are combined. These several wires leading to the proper terminals in the terminal box of the motor enable it to run on either circuit.

' Referring now to Fig. 4, the cover is made of insulating material and is provided with two parallel slots 2! and 22 adapted to receive the contact fingers Hi and i3 above described, respectively, when in the positions shown in Fig, 5, and a, third slot 23 which is adapted to receive the contact finger l3 when it is in the position shown in Fig. 'l. The cover 20 is removably attached to the plug 9 by any suitable means, such as by screws passing through the holes 24 therein to hold the insert and the contact fingers l9 and 13 in their proper positions. Thus, all that is necessary to do in changing the voltage of the circuit to which the motor is to be plugged, is to first remove the cover 20, then change the position of the insert 12, and then replac the cover 29.

Thus I have provided a plug which is permanently attached to the four wires 0., b, c and d, which are extensions of the motor wiring to the terminal box, and which is provided with a fixed contact finger l0 and a movable contact finger l3; which may be easily shifted from one position to the other; and which is held in such position by the cover 20 until it is again desired to shift it back to its first position. 7

It is, of course, understood that changes may be made in th construction of my improved plug without departing from the spirit of my invention as outlined in the appended claims.

Having describedmy invention, what I claim and desire to secure by Letters: Patent, is:

1. In an electric plug having a number of circuit wires connected thereto and leading therefrom and adapted tobe connected to either of 4 two circuits of different voltages, comprising a fixed contact finger mounted on the plug and in constant connection with one of said circuit wires; a movable body mounted on the plug; a second contact finger mounted on said movable body; fixed plates mounted on said plug adjacent to said body and connected to said circuit wires; and plates mounted on said body and adapted to contact th plates mounted on the plug one said plate being connected to said second contact finger, whereby when said second contact finger is in one position said plates on said body contact certain plates on the plug and when said second contact finger is in its other position said plates on said body contact other plates on .the plug.

2. In an electric plug, having a number of circuit'wires attached thereto and leading there- 1 from; the-combination of an insulating body; a

fixed contact finger extending therefrom and electrically connected to one said circuit wire; a cavity inthe end of said plug; an equal number of contact plates mounted in the sides of said cavity and each electrically connected to its correspond ng circuit wire; an insert of insulating material adapted to fit in. said cavity; a complementary, contact finger mounted on said insert and extending therefrom and adapted to cooperate with said fixed contact finger for insertion in an electric outlet; and two contact plates mounted on the sides of said insert and adapted to contact said contact plates in said cavity,'one of said two ,contact plates being connected to said second contact finger.

'3. An electric plug as set forth in claim 2, wherein saidcavity is square andwherein said insert may be placed therein in either of two positions, whereby the relative positions of said two contact fingers may be changed, and whereby the contacts between the plates on the insert and in the cavity are changed.

4. An electric plug, asset forth in claim 2, together with a coverremovably secured to the end of the plug and adapted to hold said insert in said cavity.

MAX M. GUERNSEY.

REFERENCES CITED The following references are. of record in the file of this patent:

UNITED STATES PATENTS Newton Aug. 5, 1941 

